1 /*
2 * $Header: /home/cvs/jakarta-commons/betwixt/src/java/org/apache/commons/betwixt/io/BeanCreateRule.java,v 1.11 2002/08/29 21:40:29 rdonkin Exp $
3 * $Revision: 1.11 $
4 * $Date: 2002/08/29 21:40:29 $
5 *
6 * ====================================================================
7 *
8 * The Apache Software License, Version 1.1
9 *
10 * Copyright (c) 1999-2002 The Apache Software Foundation. All rights
11 * reserved.
12 *
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
15 * are met:
16 *
17 * 1. Redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer.
19 *
20 * 2. Redistributions in binary form must reproduce the above copyright
21 * notice, this list of conditions and the following disclaimer in
22 * the documentation and/or other materials provided with the
23 * distribution.
24 *
25 * 3. The end-user documentation included with the redistribution, if
26 * any, must include the following acknowlegement:
27 * "This product includes software developed by the
28 * Apache Software Foundation (http://www.apache.org/)."
29 * Alternately, this acknowlegement may appear in the software itself,
30 * if and wherever such third-party acknowlegements normally appear.
31 *
32 * 4. The names "The Jakarta Project", "Commons", and "Apache Software
33 * Foundation" must not be used to endorse or promote products derived
34 * from this software without prior written permission. For written
35 * permission, please contact apache@apache.org.
36 *
37 * 5. Products derived from this software may not be called "Apache"
38 * nor may "Apache" appear in their names without prior written
39 * permission of the Apache Group.
40 *
41 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
42 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
43 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
44 * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
45 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
46 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
47 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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49 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
50 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
51 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
52 * SUCH DAMAGE.
53 * ====================================================================
54 *
55 * This software consists of voluntary contributions made by many
56 * individuals on behalf of the Apache Software Foundation. For more
57 * information on the Apache Software Foundation, please see
58 * <http://www.apache.org/>;.
59 *
60 * $Id: BeanCreateRule.java,v 1.11 2002/08/29 21:40:29 rdonkin Exp $
61 */
62 package org.apache.commons.betwixt.io;
63
64 import java.util.HashMap;
65 import java.util.Iterator;
66 import java.util.List;
67 import java.util.Map;
68
69 import org.apache.commons.betwixt.AttributeDescriptor;
70 import org.apache.commons.betwixt.ElementDescriptor;
71 import org.apache.commons.betwixt.XMLBeanInfo;
72 import org.apache.commons.betwixt.XMLIntrospector;
73 import org.apache.commons.betwixt.expression.Context;
74 import org.apache.commons.betwixt.expression.MethodUpdater;
75 import org.apache.commons.betwixt.expression.Updater;
76 import org.apache.commons.betwixt.digester.XMLIntrospectorHelper;
77
78 import org.apache.commons.digester.Rule;
79 import org.apache.commons.digester.Rules;
80 import org.apache.commons.digester.Digester;
81
82 import org.apache.commons.logging.Log;
83 import org.apache.commons.logging.LogFactory;
84
85 import org.xml.sax.Attributes;
86
87 /*** <p><code>BeanCreateRule</code> is a Digester Rule for creating beans
88 * from the betwixt XML metadata.</p>
89 *
90 * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
91 * @author <a href="mailto:martin@mvdb.net">Martin van den Bemt</a>
92 * @version $Revision: 1.11 $
93 */
94 public class BeanCreateRule extends Rule {
95
96 /*** Logger */
97 private static final Log log = LogFactory.getLog( BeanCreateRule.class );
98
99 /*** Set log to be used by <code>BeanCreateRule</code> instances */
100 public static void setLog(Log log) {
101 log = log;
102 }
103
104 /*** The descriptor of this element */
105 private ElementDescriptor descriptor;
106 /*** The Context used when evaluating Updaters */
107 private Context context;
108 /*** Have we added our child rules to the digester? */
109 private boolean addedChildren;
110 /*** In this begin-end loop did we actually create a new bean */
111 private boolean createdBean;
112 /*** The type of the bean to create */
113 private Class beanClass;
114 /*** The prefix added to digester rules */
115 private String pathPrefix;
116 /*** Beans digested indexed by <code>ID</code> */
117 private Map beansById = new HashMap();
118 /*** Use id's to match beans? */
119 private boolean matchIDs = true;
120
121 /***
122 * Convenience constructor which uses <code>ID's</code> for matching.
123 */
124 public BeanCreateRule(
125 ElementDescriptor descriptor,
126 Class beanClass,
127 String pathPrefix )
128 {
129 this( descriptor, beanClass, pathPrefix, true );
130 }
131
132 /***
133 * Constructor taking a class.
134 */
135 public BeanCreateRule(
136 ElementDescriptor descriptor,
137 Class beanClass,
138 String pathPrefix,
139 boolean matchIDs ) {
140 this(
141 descriptor,
142 beanClass,
143 new Context(),
144 pathPrefix,
145 matchIDs);
146 }
147
148 /***
149 * Convenience constructor which uses <code>ID's</code> for matching.
150 */
151 public BeanCreateRule( ElementDescriptor descriptor, Class beanClass ) {
152 this( descriptor, beanClass, true );
153 }
154
155 /***
156 * Constructor uses standard qualified name.
157 */
158 public BeanCreateRule( ElementDescriptor descriptor, Class beanClass, boolean matchIDs ) {
159 this( descriptor, beanClass, descriptor.getQualifiedName() + "/" , matchIDs );
160 }
161
162 /***
163 * Convenience constructor which uses <code>ID's</code> for match.
164 */
165 public BeanCreateRule(
166 ElementDescriptor descriptor,
167 Context context,
168 String pathPrefix ) {
169 this( descriptor, context, pathPrefix, true );
170 }
171
172 /***
173 * Constructor taking a context.
174 */
175 public BeanCreateRule(
176 ElementDescriptor descriptor,
177 Context context,
178 String pathPrefix,
179 boolean matchIDs ) {
180 this(
181 descriptor,
182 descriptor.getSingularPropertyType(),
183 context,
184 pathPrefix,
185 matchIDs );
186 }
187
188 /***
189 * Base constructor (used by other constructors).
190 */
191 private BeanCreateRule(
192 ElementDescriptor descriptor,
193 Class beanClass,
194 Context context,
195 String pathPrefix,
196 boolean matchIDs ) {
197 this.descriptor = descriptor;
198 this.context = context;
199 this.beanClass = beanClass;
200 this.pathPrefix = pathPrefix;
201 this.matchIDs = matchIDs;
202 if (log.isTraceEnabled()) {
203 log.trace("Created bean create rule");
204 log.trace("Descriptor=" + descriptor);
205 log.trace("Class=" + beanClass);
206 log.trace("Path prefix=" + pathPrefix);
207 }
208 }
209
210
211
212 // Rule interface
213 //-------------------------------------------------------------------------
214
215 /***
216 * Process the beginning of this element.
217 *
218 * @param attributes The attribute list of this element
219 */
220 public void begin(Attributes attributes) throws Exception {
221 log.debug( "Called with descriptor: " + descriptor + " propertyType: " + descriptor.getPropertyType() );
222
223 if (log.isTraceEnabled()) {
224 int attributesLength = attributes.getLength();
225 if (attributesLength > 0) {
226 log.trace("Attributes:");
227 }
228 for (int i=0, size=attributesLength; i<size; i++) {
229 log.trace("Local:" + attributes.getLocalName(i));
230 log.trace("URI:" + attributes.getURI(i));
231 log.trace("QName:" + attributes.getQName(i));
232 }
233 }
234
235
236
237 // XXX: if a single rule instance gets reused and nesting occurs
238 // XXX: we should probably use a stack of booleans to test if we created a bean
239 // XXX: or let digester take nulls, which would be easier for us ;-)
240 createdBean = false;
241
242 Object instance = null;
243 if ( beanClass != null ) {
244 instance = createBean(attributes);
245 if ( instance != null ) {
246 createdBean = true;
247
248 context.setBean( instance );
249 digester.push(instance);
250
251
252 // if we are a reference to a type we should lookup the original
253 // as this ElementDescriptor will be 'hollow' and have no child attributes/elements.
254 // XXX: this should probably be done by the NodeDescriptors...
255 ElementDescriptor typeDescriptor = getElementDescriptor( descriptor );
256 //ElementDescriptor typeDescriptor = descriptor;
257
258 // iterate through all attributes
259 AttributeDescriptor[] attributeDescriptors = typeDescriptor.getAttributeDescriptors();
260 if ( attributeDescriptors != null ) {
261 for ( int i = 0, size = attributeDescriptors.length; i < size; i++ ) {
262 AttributeDescriptor attributeDescriptor = attributeDescriptors[i];
263
264 // The following isn't really the right way to find the attribute
265 // but it's quite robust.
266 // The idea is that you try both namespace and local name first
267 // and if this returns null try the qName.
268 String value = attributes.getValue(
269 attributeDescriptor.getURI(),
270 attributeDescriptor.getLocalName()
271 );
272
273 if (value == null) {
274 value = attributes.getValue(attributeDescriptor.getQualifiedName());
275 }
276
277 if (log.isTraceEnabled()) {
278 log.trace("Attr URL:" + attributeDescriptor.getURI());
279 log.trace("Attr LocalName:" + attributeDescriptor.getLocalName() );
280 log.trace(value);
281 }
282
283 Updater updater = attributeDescriptor.getUpdater();
284 log.trace(updater);
285 if ( updater != null && value != null ) {
286 updater.update( context, value );
287 }
288 }
289 }
290
291 addChildRules();
292
293 // add bean for ID matching
294 if ( matchIDs ) {
295 // XXX need to support custom ID attribute names
296 // XXX i have a feeling that the current mechanism might need to change
297 // XXX so i'm leaving this till later
298 String id = attributes.getValue( "id" );
299 if ( id != null ) {
300 beansById.put( id, instance );
301 }
302 }
303 }
304 }
305 }
306
307 /***
308 * Process the end of this element.
309 */
310 public void end() throws Exception {
311 if ( createdBean ) {
312
313 // force any setters of the parent bean to be called for this new bean instance
314 Updater updater = descriptor.getUpdater();
315 Object instance = context.getBean();
316
317 Object top = digester.pop();
318 if (digester.getCount() == 0) {
319 context.setBean(null);
320 }else{
321 context.setBean( digester.peek() );
322 }
323
324 if ( updater != null ) {
325 if ( log.isDebugEnabled() ) {
326 log.debug( "Calling updater for: " + descriptor + " with: " + instance + " on bean: " + context.getBean() );
327 }
328 updater.update( context, instance );
329 }
330
331 }
332 }
333
334 /***
335 * Tidy up.
336 */
337 public void finish() {
338 // clear beans map
339 beansById.clear();
340 }
341
342
343 // Implementation methods
344 //-------------------------------------------------------------------------
345
346 /*** Factory method to create new bean instances */
347 protected Object createBean(Attributes attributes) throws Exception {
348 //
349 // See if we've got an IDREF
350 //
351 // XXX This should be customizable but i'm not really convinced by the existing system
352 // XXX maybe it's going to have to change so i'll use 'idref' for nows
353 //
354 if ( matchIDs ) {
355 String idref = attributes.getValue( "idref" );
356 if ( idref != null ) {
357 // XXX need to check up about ordering
358 // XXX this is a very simple system that assumes that id occurs before idrefs
359 // XXX would need some thought about how to implement a fuller system
360 Object bean = beansById.get( idref );
361 if ( bean != null ) {
362 return bean;
363 }
364 }
365 }
366
367 try {
368 return beanClass.newInstance();
369 }
370 catch (Exception e) {
371 log.warn( "Could not create instance of type: " + beanClass.getName() );
372 return null;
373 }
374 }
375
376 /*** Adds the rules to the digester for all child elements */
377 protected void addChildRules() {
378 if ( ! addedChildren ) {
379 addedChildren = true;
380
381 addChildRules( pathPrefix, descriptor );
382 }
383 }
384
385 /*** Add child rules for given descriptor at given prefix */
386 protected void addChildRules(String prefix, ElementDescriptor currentDescriptor ) {
387 BeanReader digester = getBeanReader();
388
389 if (log.isTraceEnabled()) {
390 log.trace("Adding child rules for " + currentDescriptor + "@" + prefix);
391 }
392
393 // if we are a reference to a type we should lookup the original
394 // as this ElementDescriptor will be 'hollow' and have no child attributes/elements.
395 // XXX: this should probably be done by the NodeDescriptors...
396 ElementDescriptor typeDescriptor = getElementDescriptor( currentDescriptor );
397 //ElementDescriptor typeDescriptor = descriptor;
398
399
400 ElementDescriptor[] childDescriptors = typeDescriptor.getElementDescriptors();
401 if ( childDescriptors != null ) {
402 for ( int i = 0, size = childDescriptors.length; i < size; i++ ) {
403 final ElementDescriptor childDescriptor = childDescriptors[i];
404 if (log.isTraceEnabled()) {
405 log.trace("Processing child " + childDescriptor);
406 }
407
408 String propertyName = childDescriptor.getPropertyName();
409 String qualifiedName = childDescriptor.getQualifiedName();
410 if ( qualifiedName == null ) {
411 log.trace("Ignoring");
412 continue;
413 }
414 String path = prefix + qualifiedName;
415 // this code is for making sure that recursive elements
416 // can also be used..
417 if (qualifiedName.equals(currentDescriptor.getQualifiedName())) {
418 log.trace("Creating generic rule for recursive elements");
419 int index = -1;
420 if (childDescriptor.isWrapCollectionsInElement()) {
421 index = prefix.indexOf(qualifiedName);
422 if (index == -1) {
423 // shouldn't happen..
424 continue;
425 }
426 int removeSlash = prefix.endsWith("/")?1:0;
427 path = "*/" + prefix.substring(index, prefix.length()-removeSlash);
428 }else{
429 // we have a element/element type of thing..
430 ElementDescriptor[] desc = currentDescriptor.getElementDescriptors();
431 if (desc.length == 1) {
432 path = "*/"+desc[0].getQualifiedName();
433 }
434 }
435 Rule rule = new BeanCreateRule( childDescriptor, context, path, matchIDs);
436 addRule(path, rule);
437 continue;
438 }
439 if ( childDescriptor.getUpdater() != null ) {
440 if (log.isTraceEnabled()) {
441 log.trace("Element has updater "
442 +((MethodUpdater) childDescriptor.getUpdater()).getMethod().getName());
443 }
444 if ( childDescriptor.isPrimitiveType() ) {
445 addPrimitiveTypeRule(path, childDescriptor);
446 }
447 else {
448 // add the first child to the path
449 ElementDescriptor[] grandChildren = childDescriptor.getElementDescriptors();
450 if ( grandChildren != null && grandChildren.length > 0 ) {
451 ElementDescriptor grandChild = grandChildren[0];
452 String grandChildQName = grandChild.getQualifiedName();
453 if ( grandChildQName != null && grandChildQName.length() > 0 ) {
454 if (childDescriptor.isWrapCollectionsInElement()) {
455 path += '/' + grandChildQName;
456 }
457 else{
458 path = prefix + grandChildQName;
459 }
460 }
461 }
462
463 // maybe we are adding a primitve type to a collection/array
464 Class beanClass = childDescriptor.getSingularPropertyType();
465 if ( XMLIntrospectorHelper.isPrimitiveType( beanClass ) ) {
466 addPrimitiveTypeRule(path, childDescriptor);
467 }
468 else {
469 Rule rule = new BeanCreateRule( childDescriptor, context, path + '/', matchIDs );
470 addRule( path, rule );
471 }
472 }
473 } else {
474 log.trace("Element does not have updater");
475 }
476
477 ElementDescriptor[] grandChildren = childDescriptor.getElementDescriptors();
478 if ( grandChildren != null && grandChildren.length > 0 ) {
479 log.trace("Adding grand children");
480 addChildRules( path + '/', childDescriptor );
481 }
482 }
483 }
484 }
485
486 /***
487 * Get the associated bean reader.
488 */
489 protected BeanReader getBeanReader() {
490 // XXX this breaks the rule contact
491 // XXX maybe the reader should be passed in the constructor
492 return (BeanReader) getDigester();
493 }
494
495 /*** Allows the navigation from a reference to a property object to the descriptor defining what
496 * the property is. i.e. doing the join from a reference to a type to lookup its descriptor.
497 * This could be done automatically by the NodeDescriptors. Refer to TODO.txt for more info.
498 */
499 protected ElementDescriptor getElementDescriptor( ElementDescriptor propertyDescriptor ) {
500 Class beanClass = propertyDescriptor.getSingularPropertyType();
501 if ( beanClass != null ) {
502 XMLIntrospector introspector = getBeanReader().getXMLIntrospector();
503 try {
504 XMLBeanInfo xmlInfo = introspector.introspect( beanClass );
505 return xmlInfo.getElementDescriptor();
506 }
507 catch (Exception e) {
508 log.warn( "Could not introspect class: " + beanClass, e );
509 }
510 }
511 // could not find a better descriptor so use the one we've got
512 return propertyDescriptor;
513 }
514
515 /***
516 * Adds a new Digester rule to process the text as a primitive type
517 */
518 protected void addPrimitiveTypeRule(String path, final ElementDescriptor childDescriptor) {
519 Rule rule = new Rule() {
520 public void body(String text) throws Exception {
521 childDescriptor.getUpdater().update( context, text );
522 }
523 };
524 addRule( path, rule );
525 }
526
527 /***
528 * Safely add a rule with given path.
529 */
530 protected void addRule(String path, Rule rule) {
531 Rules rules = digester.getRules();
532 List matches = rules.match(null, path);
533 if ( matches.isEmpty() ) {
534 if ( log.isDebugEnabled() ) {
535 log.debug( "Adding digester rule for path: " + path + " rule: " + rule );
536 }
537 digester.addRule( path, rule );
538 }
539 else {
540 if ( log.isDebugEnabled() ) {
541 log.debug( "Ignoring duplicate digester rule for path: " + path + " rule: " + rule );
542 }
543 }
544 }
545
546 /***
547 * Return something meaningful for logging.
548 */
549 public String toString() {
550 return "BeanCreateRule [path prefix=" + pathPrefix + " descriptor=" + descriptor + "]";
551 }
552
553 }
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